Mike Johnston’s signature homelessness initiative quietly surpassed the sheltering goal he set for it this year, but the Denver mayor and his top advisers are eyeing a more challenging milestone in 2025. As the city brings at least 2,000 people off the streets next year — roughly matching the number sheltered in the initiative since its launch last fall — the bigger goal, in some ways, will be to place at least 1,000 participants in more permanent housing situations.